Galaxy Space Universe Comfortable Pillow Case 18x18 (Twin sides) It is two side printing pillow case which do not contain pillow core. Material:50% cotton, 50% polyester. It's a zippered pillow case, with a zippered opening on the side. With pre-shrunk fabric, this pillowcase is washable at 60. Having this soft custom pillowcase will add both comfort and style to your home.